Intravenous busulfan and melphalan versus high-dose melphalan as a conditioning regimen for early autologous stem cell transplantation in patients with multiple myeloma: a propensity score-matched analysis.

We compared the efficacy and toxicity of busulfan and melphalan (BUMEL) and those of high-dose melphalan (HDMEL) as conditioning regimens for autologous stem cell transplantation (ASCT) in patients with multiple myeloma (MM) through a propensity score-matched analysis. No significant difference in the complete response and overall response rate after ASCT was observed between BUMEL and HDMEL. After a median follow-up of 37.3 months in the BUMEL group and 50.8 months in the HDMEL group, the median progression-free survival was calculated to be 32.9 months and 25.2 months (p = 0.995). With respect to non-hematologic toxicities, infections were more frequently reported in the BUMEL group (p < 0.001). Three patients who received BUMEL developed veno-occlusive disease (VOD), and all of them recovered without administration of defibrotide. In conclusion, BUMEL is an effective alternative conditioning regimen in terms of efficacy, but attention should be paid to toxicities.